Electrostatic telephone



April 9, 1929. R. NAGEL ELECTROSTATIC TELEPHONE Filed May 9, 1928Patented Apr. 9, 1929.

UNITED STATES PATENT OFFICE.

RICHARD NAGEL, OF SPAND'AU, GERMANY, ASSIGNOR TO F. AUGUST SGHROEDER, F

. NEW. YORK, N. Y.

ELECTROSTATIC TELEPHONE.

Application filed Ma 9, 1928, Serial No.

My invention relates to an electrostatic telephone and more particularlyto a telephone of the stated type, the Ob]GCtS of which include theobtaining of high ei'liciency and reliability of operation, with aconstruction which is highly practical and which may be manufactured ata comparatively low cost.

Electrostatic telephones as hitherto constructed are provided, in orderto comply with the above stated requirements, with strong, solidcapacity bodies, such as castingswhich are worked and finished by meansof special turning, grinding and polishing machines. Telephones or loudspeakers constructed in this way necessarily have considerable weightand, therefore, cause inconvenience in moving them from place to place.

One object of my invention is to remedy this defect and with this objectin view I provide, with the particular example of the invention hereshown, in lieu of the heavy undivided capacity body hitherto used, a composite body, made of sheet metal and composed of a plurality ofindividual units or members interconnected to form in their totality arigid body of. the required shape and with an absolutely plain operatingsurface. The means I employ for the interconnecting purpose may be ofvarious kinds such as clinchers, brackets, rings or similar fixtures.

In a preferred construction I employ sheet metal members or units ofsegmental shape which are to be interconnected only at their peripheraland central ends, while the radial edges thereof remain unconnected.Preferably I use for the purpose segmental sheets of a light metal oralloy of a thickness of approximately 1 millimetre and I provideperforations therein in the 'manner of a sieve. For reinforcin purposesI bend the free radial edges 0 the segmental members so that they formflanges projecting from the rear surface or side thereof, that is tosay, the surface turned awa from the diaphragm, and constituting a reiable reinforcing means.

A construction adapted to be used in combination with the capacity bodyhereinbefore described, in general may comprise a wheellike body made ofa light metal or alloy, and a preferably metallic thin sheet or foilwhich is kept under tension while being placed upon the said wheel-likebody in order to be firmly connected therewith. In one example 276,490,and in Germany April 28, 1926.

like body, as regards circumferential size, is

employed to overlie the diaphragm and the segmental members are placeduponsuch insulating ring so as to be supported peripherally by the rimportion of the wheel-like body and centrally by the hub portion thereof,with the insulating ring intermediate between the rim portion of thewheel-like body and the peripheral ends of the segmental members, andwith an insulating disk between the hub portion of the same and thecentral ends of the segmental members, so that the assembled parts willbe properly insulated.

All of the segmental members having been accurately assembled to form aclosed circular grid on the wheel-like body, an annular insulating bodyof comparatively great thickness is to be placed over and upon theperipheral ends of the segmental members. The annular body is similar tothe rim of the wheel-likebody, in diametrical respects, and

.both bodies are provided with registering holes for the reception ofscrews for firmly uniting the two bodies with the capacity grid and thediaphragm inclusive of the insulating means therebetween, the diaphragmthus being safely held in place to maintain the full of its tensionpreviously imparted to it. The segmental members constituting thecapacity body preferably may be of the same size and shape. It goeswithout saying, however, as to certain phases of-the invention that theymay be made of different areas and given any different sizes as regardsthe angle formed by the two radial edges of each member, and thecapacity body may be composed of any desired number of segmental membersof the same size or of different sizes.

With the above recited objects and general purposes in view, theinvention resides in. the novel features of construction andcombinations of parts as set forth in the following specificatiomasparticularlypointed out in the, appended claims and illustrated in theaccompanying drawings, it beingunderstood that the right is reserved toembodiments other than those actually illustrated herein, to the fullextent indicated by the general meaning of the terms in which the claimsare ex ressed.

n the accompanying drawings, forming surface or grid-plate composed of anumber of segmental members of like shape and size Figure 2 is a similarview of the same with all of the parts constituting thetelephone dulyassembled, but partially broken away to expose underlying parts; Figure3 is a sectional'view, the section being taken on the I line AB ofFigure 1;

Figure 4xis a perspective view of one of the segmental members; Figure5is a sectional view. with the section taken on the line G-D of Figure4; and Figure 6 is a perspective view of one of the segmentsconstituting the annular insulating body.

.Parts which are repeated in the severalfigures bear the same referencecharacters in each case.

Referring to Figure 1 the wheel-like body 10 preferably made of asuitable aluminium alloy, comprises a rim 11, spokes 12 and a hub 13having a threaded central bore 14 for the reception of a screw. The thinmetallic sheetor foil constituting-the diaphragm 15 is supported by thewheel 10 and afiixed thereto while being kept under suitable tension.

The segmental members 16 to be mounted over and upon the diaphragm 15 inparallel relationship thereto, are made of a suitable sheet metal suchas an aluminium alloy, and are provided throughout the whole areabetween the turned-up-radial edges or flanges 18 with smallholes orperforations '17 of circular or any, other appropriate form, while theperipheral ends 19 and the central ends 20 of the segm'ntal'meinbers 16are preferably not perforated, aswill be seen in Figure 4;. 1

The area 19 forming the larger peripheral end of each segmental member16 may be provided with two holes 21 and 22, a lateral nose or lug 24:on one side and a correspondingly shaped recess 23 on the other side forthe reception of the lugof the adjacent memher when the members are dulyassembled to form a circular body. In thisway the assemblage of themembers'16 to constitute the latter may be effected in a ready mannerand any unintentional displacement of the members with relation to eachother during the assembling and mounting operations is prevented.

Inserted between the wheel 10 and the segmental members 16 is aninsulating sheet or membrane 25 which has two holes 26 corresponding, asregards location to the holes fornse in connection with an electrostatictelephone having a capacity 21 and 22 of the'area 19. Instead of amembrane such as 25, any other insulating members or even an insulatingring of appropriate shape and size to conform to the rim 11 of thewheel, may be emplo ed.

The smaller central en s 20 of the segmental members 16 are supported bythe hub 13 of the wheel 10 and a suitable insulating member may likewisebe interposed between the ends 20 and the hub 13. This insulating membermay be the sheet or membrane 25 or else a separate insulating means suchas a small disk or the like or both may be used 'for the purpose inView.

When the parts so far described are properly assembled, they are to beinterconnected in the following manner in order to constitute a rigidlyframed structure. I place a rubber ring or washer 27 on the central partof the capacity grid so that the ends 20 of the segmental members 16will lie between the washer 27 and the hub 13 of the wheel 10, asclearly shown in Figure 3, and

on top of the washer 27 I place a metallic disk 28 having a central borefor the accommodation of a screw 29, whereupon I firmly connect the disk28 with the hub 13 by means of the-screw 29 engaging in the threadedbore 14 of the hub.

When the parts thus have been rigidl connected at the centre of the telehone roceed to firmly unite the same at t e eri ery by mounting anannular body of insu ating material on the rim 11 of the wheel with theparts 16, 25 and 16lying between the wheel plurality of members of sheetmetal, and

means for assembling and interconnecting the said members to form arigid structure.

2. An electrostatic telephone, comprising a diaphragm, a capacity bodycomposed of segmental members of sheet metal arranged radiallyclose byeach other, and means for interconnecting the said members to form arigid structure.

3. An electrostatic tele hone, comprising a diaphragm, a capacit odycomposed of segmental membersof eet metal arranged radially close toeach other, and means for interconnectin the central smaller ends andthe peripherafiargerends, respectively, with each other.

4. An electrostatic telepgone, comprising a diaphragm, a capacity dycomposed of segmental members having lateral or radial flanges andassembled with their flanges close by each other, and means forinterconnecting the said members to form a rigid structure.

5. An electrostatic telephone, comprising a vibratory diaphragm, acapacity body cooperating with said diaphragm including a plurality ofpressed sheet metal members, each formed with struck-up portionsextending in a direction away from the dia hragm for Iionsiring therelative rigidity of t e capacity 6. An electrostatic telephonecomprising a diaphragm, a capacity bodycomposed .of a plurality ofsectionsopposed to" said dia phragm, means for interconnecting saidsections to form a relatively ri id structure, and means individual toeach 0 said sections for clamping the opposed diaphragm area in re spectto said sections respectively.

7. An electrostatic telephone, comprising'a diaphragm, a capacity bodycomposed o a plurality of sections opposed to said diaphragm, saidsections being formed with interlocking lug portions and recesses, and

means for clamping said sections in respect to each other to form arelatively rigid structure.

8. An electrostatic telephone comprising a diaphragm includingconductive means, a

capacity body composed of a plurality of sections respectively opposedto said diaphragm, and resilient means for clamping portions of saidsections in respect to said dlaphragm.

9. An electrostatic telephone comprising a diaphragm includingconductive means, a supporting frame member, a capacity body comprisinga plurality of sections opposed to said diaphragm, and clamping means atthe mid-portion of the diaphragm for interconnecting said members.

10. An electrostatic telephone construction comprising a cast framemember, a perforated metal capacity body having struckup portionsstrengthening the same, and a vibratory diaphragm clamped in respect tosaid frame to extend over and to cooperate with said capacity body.

11. An electrostatic telephone construction comprisin a conductivevibratory diaphragm e ement, a plurality of relatively rigid capacitelements opposed to said diaphragm, a rame structure, and common meansfor clamping said diaphragm and said capacity members in respect to saidframe structure.

In testimony whereof I have signed my name to this specification.

RICHARD NAGEL.

